DJ injection demonstration (sort of)

[syncrosimon]

Sorry to bore you, but I put a video together a few weeks ago about the workings of the DJ injection. The lambda probe I have is an aftermarket Stack one that reads the state of tune on my engine. The DJ is a basic form of injection where the ECU uses look up tables to determine the quantity of fuel going into the engine by varying the time the injectors are open. The mixture is also meddled with by vacuum operating on the fuel pressure regulator. I have fitted a tee on the fuel hose where I can attach a gauge to check all is well.

The MV is the more advanced version of the DJ and incorporates a lambda into the ECU and constantly monitors the mixture. The lower compression engine is also slightly easier to live with sipping on regular octane un-leaded. The MV also electronically alters the ignition mapping whereas the DJ relies on vacuum and centrifuge to alter things.

The purpose of the video really is to show how well the DJ Ecu keeps things as they should be, as the ECU really has no idea whatsoever what the engine is doing, and just remembers what the german boffins told it it should be doing under all the pre-determined conditions they could think of about 30 years ago!!

http://www.youtube.com/watch?v=7G39McZj ... TsqzFAAAAA" onclick="window.open(this.href);return false;

[PetenAli]

Thanks for putting that vid up Simon - its helped me learn a bit more about my DJ. Nice steady oil temp and pressure as well! I've now decided that, like you, I'm going to stick with the DJ so all info is helpful!

[KINGPRAWN]

Thanks for putting that vid up Simon - its helped me learn a bit more about my DJ. Nice steady oil temp and pressure as well! I've now decided that, like you, I'm going to stick with the DJ so all info is helpful!

...... Yeh I'll be keeping the faith too!!!!!

[KINGPRAWN]

Very interesting watching!... Sounds very crisp too. Any chance of an idiots guide to the fitting of the gauges and the pressure gauge in the engine bay please???

[silverbullet]

Brilliant! Fuel injection in a nutshell. What brand instruments have you got fitted Simon (it's probably in another thread isn't it?) as I must upgrade from my DIY lambda voltage set-up, it's too twitchy and badly affected by voltage drop-off when the headlights are on! So much for the plug-in voltage regulator...
PS your DJ sounds very sweet when revved

[ghost123uk]

and badly affected by voltage drop-off when the headlights are on! So much for the plug-in voltage regulator...
PS your DJ sounds very sweet when revved

What voltage does the probe need ?

I ask because I can easily supply a simple circuit for producing a very smooth and accurate DC voltage.

[silverbullet]

I'll have to check but the digital voltmeter I used was a standard RS part, lambda probe is generic and supply is a ciggy-lighter multi-voltage jobbie that I hard-wired to the meter. I worked well enough to hike the lpg mileage up from 16 to 20 with a simple tune-up!

[KINGPRAWN]

I'll have to check but the digital voltmeter I used was a standard RS part, lambda probe is generic and supply is a ciggy-lighter multi-voltage jobbie that I hard-wired to the meter. I worked well enough to hike the lpg mileage up from 16 to 20 with a simple tune-up!

What exactly is involved in your basic tune up.... Parts or adjusting stuff???

[silverbullet]

Whoops, we're getting a bit across purposes here! My interest was in Simon's choice of instrumentation with a view to improving my Heath Robinson mixture testing set-up. I used it to get an lpg system closer to correct running.

[ghost123uk]

lambda probe is generic and supply is a ciggy-lighter multi-voltage jobbie

as this is Simon's thread, regarding his set up, I have sent you a p.m. re this.

[syncrosimon]

Very interesting watching!... Sounds very crisp too. Any chance of an idiots guide to the fitting of the gauges and the pressure gauge in the engine bay please???

Here is the original thread on the oil cooler and other gauges.

https://club8090.co.uk/forum/viewtopic.php?f=4&t=59595" onclick="window.open(this.href);return false;

I would say that really the only gauge you need is the oil pressure, the others are for interest more than anything. I got the Lambda because I was going to play around with the spring settings on the Air Flow Meter. But having seen how the engine behaves with the Lambda I have seen that it is not necessary. VW yet again got it right in the first place.

The oil pressure will drop if the oil temp goes high, so keeping an eye on the pressure and knowing what it should be at certain motorway speeds and slowing down if the pressure starts to drop is much cheaper than going the cooler route. I am sure that the catastrophic WBX failures that so many have are due to low oil pressure for one reason or another, at least if you can see the pressure fading away you can stop before it goes kaboom. The oil temp goes up very fast under full throttle on the motorway.

Simon.

[syncrosimon]

What brand instruments have you got fitted Simon

The Lambda is a Stack, and the oil temp and pressure are VDO's, The Stack is very nice, but pricey. The unit has its own harness, and voltage regulator built in. I had to lengthen the harness, to get the gauge to the front and consulted Stack in Bicester about how to go about it. They stated that the harness is tuned to length and that the longer wires would effect the reading, but only by a very small amount. A new harness is 30 quid, but the gauge would need to be in the engine bay or in the rear cupboard.

The lambda just gives me confidence on long motorway trips that all is weel with the engine, it helps psychologically on 500 mile days. And thats what the other gauges are for, peace of mind really.

The oil pressure sender is the dual pole type which keeps the buzzer of doom. I get 12-14 psi (around 1 bar) at tick over hot, and 3.2 bar 45 psi at 70mph +. The oil pressure has not changed since I fitted it. I now use an oil filter from the land rover V8's and tdi's.

[syncrosimon]

lambda probe is generic and supply is a ciggy-lighter multi-voltage jobbie

as this is Simon's thread, regarding his set up, I have sent you a p.m. re this.

It's all good stuff.

[KarlT]

Fasinating, I'm on a huge DJ learning curve at the moment (See my engine woes thread in Tech Mech) As said, nice sounding/driving engine.
Thanks for taking the time Simon.

[silverbullet]

Thanks Simon. Re: oil pressure, when I rebuilt my DG i found that the replacement oil pump gasket (Brickwerks set) was rediculously thick, in the order of 0.3mm compared to the OEM 0.1mm. so I re-worked the pump body to take a large "O" ring, thus reducing the pump gear end-float to around 0.05mm and improve pumping efficiency.
I have yet to fit a pressure gauge to know how effective this has been on a used crank and bearings; the only oil leak I have is a tiny weep from the camshaft bore plug behind the flywheel, possibly due to higher than usual pressures. Well, I hope so!